Nest Thermostat notifications are late, missing or excessive

The checks in more detail

Apple and Android both let you set per-app notification settings, so check Google Home's entry. If the thermostat is offline, it cannot tell you anything, so a missing alert may be a lost connection, which the app shows as Offline. Make sure you are signed in with the account that owns the home, and that notifications are enabled for that home. Some alerts depend on your equipment. Temperature alerts work only when you have set the limits, and a heating or cooling alert needs the thermostat to detect a fault, which basic wiring may not report.

An alert that a filter needs changing is a reminder set by you or by the runtime, not a sensor. A low battery alert is a power warning that the thermostat gives when its internal battery is low, which usually means the C-wire or power connection is weak; Good Home Automation's guide lists the fixes. If notifications arrive on one phone and not another, the second phone may not have notifications on, or may be signed in to another account. Reinstall the app if alerts stop after an update.

Test by changing the target temperature and seeing whether a confirmation arrives, and check the thermostat's own screen for an alert icon. Some owners find alerts about system status mixed with energy reports and think notifications are broken when it is only a different type of message. Open the notification settings and read each type's description. Turn off the types you do not need, so that important ones, such as a lost connection or a temperature extreme, stand out. Check the Google Home app's notification history to see whether alerts are arriving but being hidden by your phone's settings.